1. Technical Field of the Invention
The present invention relates to aids for filling hypodermic syringes with fluid medications from vials with penetrable caps. In particular, it relates to a mechanical aid for enabling the easy introduction of the needle tip of a hypodermic syringe into a capped vial of liquid medication at the proper location in the cap, to the proper depth, and the subsequent loading of the syringe with the desired volume of medication for injection.
2. Background Art
Fluid medication for hypodermic injection is commonly packaged for dispensing in standard size vials or ampoules, the caps of which are penetrable by the needle tip of a syringe for loading the medication directly into the syringe. The typical syringe is configured with a transparent barrel, with markings indicating the volume of fluid contained in the barrel by the location or depth of the plunger in the barrel.
A skilled health care provider preparing to give an injection typically holds the vial between the thumb and forefinger or between the first two fingers of one hand, with the cap end of the vial in her palm. Holding the syringe in the opposite hand, with the syringe plunger fully depressed into the syringe, she skillfully introduces the needle tip into the vial. She then carefully supports the vial and syringe in their proper relationship and up ends the vial. She then withdraws the syringe plunger, drawing medication into the syringe until she sees by the barrel markings that the desired volume has been loaded into the syringe.
As is known on a practical level to syringe and vial users, and will be readily apparent to those familiar with the limitations presented by the relative compressibility of air and fluid, the volume of fluid that can be removed from the fixed volume of a vial before make-up air is admitted is limited. Small dosages in the order of 50 cubic centimeters may be readily withdrawn in a single draw. In order to draw significantly more fluid into a syringe, it is the practice to use the syringe to draw and inject sufficient makeup air into the vial to permit the fall loading of the required dosage.
There are many circumstances where on-demand or repetitive injections are necessary, making self administration of the injection the only practical means for getting a necessary and timely dose. The requisite skill for loading the syringe can be developed by people of average dexterity and eyesight, with practice. However, there is a large class of people less eager or less able to manipulate the vial and syringe in this manner, and desirous of a mechanical aid that would facilitate the process.
In the past, there have been numerous devices adapted specifically for facilitating the measurement of the dosage drawn into a hypodermic syringe. These inventions include those disclosed in the references to Dobbins, U.S. Pat. No. 3,907,009; Ethington, U.S. Pat. No. 4,018,223; Right, U.S. Pat. No. 4,219,055; Maaki, U.S. Pat. No. 4,252,159; LaDow, U.S. Pat. No. 4,778,454; Bloom, et al., U.S. Pat. No. 4,098,276; Strong, U.S. Pat. No. 4,883,101; Lee, U.S. Pat. No. 4,274,453; Walldbauer, Jr. et al, U.S. Pat. No. 3,833,030; French, GB Pat. No. 1,179,888; and Schraga, U.S. Pat. No. 5,697,916.
While various desirable objectives and useful features are dispersed throughout this and other prior art, including various brackets for holding vials and syringes, electronic displays of dosage amounts, and selectable or positionable levers for setting dosage amounts; nowhere is there known to be disclosed, illustrated or suggested a manually operable device that provides secure, semi-automatic positioning and insertion of the syringe needle into the vial by mere closure of a holding device, in combination with an enhanced grip for withdrawing the plunger and an enhanced visual indication of the volume of medication drawn.